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In need of learning

I need to get some input on the current status of my tires' sidewall and maybe how to help make these tires last longer. As i should note, i am still very green when it comes to open track so please bear with me.

My tires are the Pilot Super sports 265/35-19 front and 295/30-19 rear. Normal pressure on track is 45-50. One of my instructors at Road ATL told me to do so to help conserve the life. I noticed after CMP at the end of DEC that the tire looked a little worn on the sidewalls. After VIR however, the driver's side is looking far more worn than the passenger side (see pictures). My alignment at CMP was stock but at VIR i was running 2.1 degrees of negative camber. Ive only run 2 track days on these tires. Am i over wearing the tires? Am i running the wrong pressures? Am I running the wrong tires?

Drivers front

001_zps095674bf.jpg

Passenger front

002_zpsba640e33.jpg

Driver rear

004_zps1632f484.jpg

Passenger rear

003_zpsc33c1fc2.jpg
 

PeteInCT

#LS-378 - So many Porsche's, so little time....
Moderator
2,848
14
Connecticut
On road courses (most of which are driven clockwise) your drivers side tires will wear much faster than your passenger side. Also, and especially if you are rotating the car through the turns, your drivers side rear will be the most worn of all. This is normal. As far as the tire pressure, 45-50 lbs hot is too much pressure, even for that non r-comp tire. If you hit a turtle at a high speeds you risk the possibility of blowing the tire. Your contact patch is also probably not optimized. I would look to try to get it down to the 42-45 lb range hot, and watch your wear marks to make sure you are still not rolling over on the sidewall of the tire too much. The Michelin Pilot super sports have a very flexible sidewall, theory being that they flex as opposed to the tire rolling over on it's side.

-Pete
 

Sesshomurai

Agree. 45-50 hot is too much. Check tirerack for suggested max pressure and keep well under. Although tire pressure is a science dependent on many variables i typically run 35 cold 42ish hot. Sometimes a few lbs less pressure in the rear for traction.
 

Grant 302

basic and well known psychic
^I'm also running these same tires, and I think Pete's got you mostly covered.

I've only got a few track days on these tires, with a target of 42 hot, and I think that's too low. Next time out with these, I'm going to try for 44-46. I currently have -2.5 camber, and I think that's probably not be enough. After looking at track photos (I'd share, but I didn't purchase them) I can verify the very soft and flexible sidewall. At Fontana, it looked like my sidewalls were about 40 degrees from the pavement in some of the tighter 2nd gear turns.

If you are running only CW, then you should try rotating L-R since these are asymmetrical tires. Or run a CCW course next.

If you have a pyrometer, then checking your tread profile temps right after you pit might help too.
 
1,255
2
GA
I ran 5 track days with my Pirelli P Zeros at 38 PSI and they wore pretty evenly ( lasted about 10K miles). I had a square setup so I was able to rotate them, which I am sure helped. A lot of your tire wear is going to be determined by how you drive. If you do your braking in a straight line before you enter the corner and go slow in-fast out, your tires will last a lot longer than if you dive bomb the corners and go fast all the way through. I purposely do the former because I can't afford to shell out money for tires and brakes after every track weekend, and this is my only car.
 

zzyzx

Steve
299
0
I run the PSS and here are my thoughts:

1. The PSS likes a lot of pressure - contrary to others, 45-50 is not too much on these tires. I keep close track of grip vs. pressure at autox and they do like the pressure. Ideally, I'd say target 45, and try to keep it below 50.

2. You need more front camber. If you expect even tire wear on the track, then you should plan to run -3.0 to -3.5 deg. of camber (possibly more). A combination of camber plates and/or bolts will get you there.

3. The PSS uses a dual compound tread, the outer 1/5 of the tire is a FAR softer/stickier compound that the rest. All else being equal (which it's not in your case), the outer edge will wear faster anyways.

Here's a helpful article on the PSS:

http://www.motortrend.com/features/performance/1101_testing_the_michelin_pilot_super_sport/viewall.html
 

Grant 302

basic and well known psychic
Thanks for sharing, Steve! ...confirms my suspicions. What size(s) are you running? My fronts are 265/35 on a 19x9, and I think it would have been better on a 9.5 wide rim.
 

zzyzx

Steve
299
0
I run 275/40F, 295/35R on the stock (non LS) wheels. These were the closest I could get to maintain the stock rake and not reduce wheel diameter, since one of my primary concerns was top speed in 2nd gear - for autox.
 

pufferfish

Supporting Vendor
1,094
66
Maryland
Nick,
I looked at your tires at the track this weekend and they looked fine for wear patterns. they look the same in the pics as i remembered. they are not rolling over at all. pressures do seem high though. i wouldn't go over 40psi hot on a street tire unless there is an indication of the sidewall rolling over (which i don't see). your overinflation may actually be the issue in your tire longevity. the higher the pressure, the less contact patch you have. less contact patch = less grip. less grip = faster tire wear.

there are lots of opinions on tire size, but too narrow of a tire up front will wear down quicker. i am of the opinion that our cars (boss or gt) should get as much front tire as you can fit. it just doesn't make sense to me that ford elected to go staggered with its weight balance. i went to 285 square on non-optimal 9" wide wheels (@40psi hot) and these street tires have held up to 2x the events of the stock 255 p-zeros and they are not even close to done...and anyone who ran with me this weekend can attest to the fact that i don't take it easy (on dry pavement, that is).
 

PeteInCT

#LS-378 - So many Porsche's, so little time....
Moderator
2,848
14
Connecticut
lots of opinion here on tire pressure for those Michelin Pilot Supersports. I run those tires on a 3200 pound track carand running 40 PSI hot was not feasible. it was just too much roll over. I seriously suspect that is 3600 pound Mustang what allow for tire pressure that low on those tires with the assumption that the driver is pushing the car somewhat and not just taking a leisurely laps. overall I would pay less attention to the exact amount of PSI and more attention to when the tire actually start to rollovercan just adjust the pressure based on that inspection.

-Pete
 

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